I partly agree with Bronia. Is there any way to establish an HTML into reviews where people could hide certain parts of their review in a spoiler tag? Instead of seeing something like: I was so sad when she died, and I really felt like it took away from the story; we'd see: I was really sad when
and I really felt it took away from the story. It's incredibly difficult to write a review without spoilers in it because many times people are simply stating their opinions and their opinions might be directly related to a spoiler.
As for the <3 feature: I am a big fan of that, but not the </3. I'm not sure if anyone has heard of a site called "Goodreads", but they have a similar feature where you can "like" reviews. The reviews with the most likes and most comments are then bumped to the top of the list and people see them first.
It might also be handy if you have a "Top 3 Reviews" feature. This would be where the reviews with the most <3 up go. It would obviously change as reviews are added and get more <3's throughout the history of the site, but maybe you could have it to where it would be updated automatically?
I also think it might be good to have a top 3 for both negative and positive reviews. I'm not talking about troll reviews, but reviews where people explain why they love or hate an anime. Like: TOP 3 POSITIVE REVIEWS and TOP 3 NEGATIVE REVIEWS. That way people could get an even amount of information to decide whether or not they'd like to watch an anime. If all the top reviews are negative or all of them are positive, it would be hard for the person to find an unbalanced opinion. Doing this would provide a well rounded amount of information.
Just throwing out some ideas :)